Sealed bag

ABSTRACT

A bag is constructed of interconnected panels each of which comprises a pair of vinyl cover sheets enclosing a fiber glass filler. The outermost edges of the cover sheets are electronically sealed to one another to trap the filler between the cover sheets; and a further electronic seal is provided between the cover sheets inward of the outermost edges thereof and extending through the fiber glass filler to keep the filler from shifting or bunching up.

United States Patent lnventor Moritz Nappe Elberon, NJ. Appl. No.857.070 Filed Sept. 11,1969 Patented June 8, 1971 Assignee Dart1ndustries,1nc.

West Bend, Wis.

SEALED BAG 6 Claims, 5 Drawing Figs.

U.S. Cl. 150/.5, l50/2.1, 161/43, 161/44 Int. Cl 13651! 33/00 Field ofSearch 161/43, 44, 45; 150/.5, 2.1

References Cited UNITED STATES PATENTS 2,781,820 2/1957 Rogers 161/433,020,183 2/1962 Calvaresi 3,073,367 1/1963 Samara PrimaryExaminer-Joseph R. Leclair Attorneys-William D. Hall, Elliott 1.Pollock, Fred C. Philpitt,

George Vande Sande, Charles F. Steininger, Robert R. Priddy and Leigh B.Taylor 16l/44X ISO/2.1

PATENTED JUN 8197i JHHHH HHH I I J.

FIG. 3.

FIG. 5.

Plastic Seals INVENTOR Moritz Noppe ATTORNEY SEALED BAG BACKGROUND OFTHE INVENTION The general concept of providing an insulating structurefor use in the fabrication of bags or the like, and consisting of a pairof plastic sheets enclosing a fibrous filler, is well known. One suchstructure is, for example, shown in my prior U.S. Pat., No. 2,834,970,issued May 20, 1958, for Sealed Pad; and structures of this general typehave been used for a variety of purposes heretofore.

When structures of the general type described are used to form portionsof an insulated carrier bag, it has been customary to merely trap thefibrous filler .within the plastic cover sheets by means of anelectronic heat sealed edge extending around the outermost periphery ofthe cover sheets and in spaced relation to the outer edge of the fibrousfiller. This, indeed, is the general arrangement shown in my said priorU.S. Pat, No. 2,834,970. In arrangements of this type, it has beennecessary to space the cover layer edge seal from the edges of the fiberglass filler since, in the absence of such spacing. arcing usuallyoccurs during the electronic sealing process with attendant burning ormelting of the plastic cover sheets. As a result, when it has beendesired to utilize an electronic heat sealing technique in thefabrication of a structure employing a fiber glass filler, the fillerhas merely been trapped within the plastic cover layer with the fillerotherwise being loose and having its edges spaced from the cover edges.

While structures of the types described above, employing a fiber glassfiller trapped between peripherally seamed plastic cover sheets, provideexcellent insulation, the insulating quali ties of the structure, andits general appearance, have been found to deteriorate after arelatively limited period of usage. This deterioration has resulted fromthe fact that there is no positive juncture between the fiber glassfiller and the enclosing plastic cover sheets; and as a result, it hasbeen found that the filler tends to fall, shift in position, and/orbunch up under the influence of gravity and other externally appliedforces, so that portions of the region between the cover sheets are nolonger filled with fiber glass material. This general problem has alsobeen recognized in the past; and in an effort to avoid this problem,alternative fabrication techniques have been sometimes used.

More particularly, in an effort toavoid shifting or bunching of a fiberglass filler, laminated insulating structures of the general typesdescribed have in the past been fabricated by laying a mat of fiberglass material between a pair of cover sheets, folding the edges of atleast one cover sheet over the edges of the fiber glass mat, and thensewing the overlapped edges to the main body of the cover sheet directlythrough the fiber glass filler. This technique actually sews'the fiberglass filler into place between the cover sheets and assures that thefiller can no longer shift in position relative to the cover sheets. Thetechnique has the disadvantage, however, that it requires a sewingoperation which is far more costly and time consuming than a heatsealing technique; and, in addition, the sewing operation perforates thecover sheet whereby the final structure is no longer completelywaterproof.

As a result of the considerations described, sealed bags fabricated bytechniques prevalent to date have either been subject to the problem offiller shifting and bunching when it has been desired to fabricate suchstructures by relatively low cost and rapid electronic sealingtechniques; or, in the alternative, bags have been fabricated by moretime consuming and expensive stitching techniques to avoid possibleshifting of the filler while simultaneously sacrificing the completelywaterproof quality of the bag. It has been considered impossible,however, to fabricate a bag by an electronic heat sealing techniquewhich achieves a seam orjuricture directly between the cover sheets andthe fiber glass filler, to avoid shifting or bunching of the filler,simply because any effort to achieve such an electronic seam by priorart techniques has uniformly resulted in arcing and melting of theplastic in the region of the attempted seam.

SUMMARY OF THE INVENTION The present invention provides a highlyimproved insulating laminate comprising a pair of thermoplastic coversheets, such as vinyl, which enclose a fiber glass matted fillermaterial. The filler material is trapped in place between the sheets bymeans of an electronic seam which is achieved between the outermostperipheries of the two cover sheets. In addition, the fiber glass filleris held in position between the sheets, and prevented from shifting orbunching up, by means ofa supplemental electronically heat sealed seampositioned inward of the peripheral seam and extending between the outercover sheets directly through the fiber glass filler. In essence,therefore, the present invention makes use of highly desirable,labor-saving electronicheat sealing techniques in fabricating thelaminate; and uses such techniques to produce, inter alia, a vinyl tovinyl seam which extends directly through an intervening fiber glasslayer so as to prevent the fiber glass material from shifting inposition relative to the outer plastic cover layers ofthe laminate.

In order to permit fabrication of the improved laminate described above,without suffering the problem of arcing and plastic melting which hascharacterized prior art techniques along the same line, the presentinvention makes use of a special die having two spaced serrated edgesoperative to form the outer peripheral and inner supplementary seamsrespectively. Two such dies are placed in opposing relation to oneanother in an electronic press of generally conventional design, havinghydraulically operated cylinders which are used to move the dies towardand away from the material to be sealed; and the press is modified toincorporate booster cylinders so as to increase the pressing force ofthe dies on the material to be sealed. The corrugated or serrated edgesof the dies are thus capable of pressing the upper and lower plasticlayers forcibly toward one another into very close proximity to oneanother. In that region of the die where the die overlies fiber glassmaterial, this forcible pressing of the plastic cover materials towardone another simultaneously presses the fiber glass layer to one side, orcompresses the fiber glass layer, so that the upper and lower plasticlayers can seal to one another notwithstanding the fact that fiber glasswas interposed between them before the pressure was applied. An initialtime period is provided to permit solid bedding of the die, andcompression of vinyl to vinyl, prior to actual application of RF to thedie; and once RF is applied after this initial time delay period, arelatively low level of power is applied for a relatively long timeinterval to decrease the possibility of arcing.

By these techniques, a completely new structure is fabricated wherein avinyl to vinyl seam is achieved directly through an intervening fiberglass insulating layer so as to keep the layer from shifting in positionor bunching up, while simultaneously preserving the integrity of thecover material and the waterproof character of the final laminate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustrative explodeddiagram of a sealed bag constructed in accordance with the presentinvention;

FIG. 2 is an illustrative diagram of a typical panel employed in thefabrication of the bag of FIG. 1;

FIG. 3 illustrates a die of the type employed to fabricate the panel ofFIG. 2;

FIG. 4 is a cross section of the die of FIG. 3 taken on line 4-4; and

FIG. 5 is a cross section of the improved laminate formed in accordancewith the present invention, and taken on line 5-5 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT A sealed bag constructed inaccordance with the present invention comprises a pair of insulatinglaminated panels 10 and 11 each of which is initially of elongatedrectangular configuration, as shown in FIG. 2. Each such panel (seeFIGS. 2 and 5) comprises a pair of generally parallel spaced air andwatertight thermoplastic sheets 12 and 13, such as vinyl, whichcompletely enclose a unitary, matted fiber glass filler 14$. The fiberglass mat 14 is trapped between sheets 12' and 13 by means of aperipheral electronically formed seal 15 disposed outwardly of andspaced from the edges of mat l4; and said mat 14 is held in positionbetween said sheets by means of a further electronically formed seal 16disposed inwardly of and generally parallel to peripheral seal 15, andextending between the vinyl layers 12 and 13 directly through theintervening fiber glass material 14. By this arrangement, a relativelynarrow elongated peripheral edge portion 14a of the fiber glass filler14 is firmly trapped between spaced seals 15 and 16, around all fouredges of each rectangular panel and 11, whereby the filler 14 isrendered incapable of shifting in any direction relative to any edge ofpanel 10 or 11.

The two panels 10 and 11 are separately fabricated and have differentdimensions as will be apparent from examination of FIG. 1. Once thesetwo panels have been fabricated, panel 10 is folded into a generallyU-shaped configuration comprising rear section lla, bottom section 11b,and top section He. The two U-shaped structures are then attached to oneanother by any appropriate technique, e.g., electronic sealing, with thefree vertical edges of end sections 1012 and We being attached to theouter vertical edges of rear section 11a, and with the bottom edges ofsections 10a, 10b and 10c being attached to the corresponding outeredges of section llb. This forms an enclosed bag with section 11c actingas a hinged cover for said bag, and an appropriate zipper may beattached around the edges of panel tlc and around the correspondingupper edges of sections 10a, 10b and 100 to permit the bag to be closedand opened as desired.

It should be noted that panels 10 and 11 can, if desired, be attached toone another, and a zipper can also be installed in the manner described,by means of a sewing technique. This achieves a very strong .juncturebetween the panels, and between the panels and zipper. All such sewing,however, should be confined to the region between seals and 16 of eachpanel 10 and 11; and therefore even though a sewing technique may beemployed, the waterproof character of the entire structure is in no wayaffected since the inner seam 16 extending around all edges of eachpanel 10 and 11 isolates the main portions of the bag from needleperforations in the sewn edges.

in order to form the double seam l5, l6, and particularly the seam 16which extends directly through fiber glass filler 14, a novel die of thetype shown in FIGS. 3 and 4 is employed.

- Die 20 is of generally rectangular configuration and is provided withan upstanding peripheral rim 2! extending around all four sides of thedie. Rim 2! is employed to form the outer peripheral seal 15, and has aserrated or corrugated edge as illustrated at 21a in FIG. 3. Each toothof the corrugated edge is spaced from the adjacent teeth byapproximately one-thirtysecond inch; and each tooth forms a seal whichis dimensioned substantially one-sixteenth inch by three thirty-secondsinch. The three thirty-seconds inch dimension is illustrated in FIG. 4by the dimension X, and the one-sixteenth inch dimension is transversethereto.

Die 20 is further provided with an upstanding flange 22 which is of thesame height as rim 21 and which is spaced inwardly thereof. Flange 22exhibits a closed rectangular configuration as shown in FIG. 3 and isused to produce inner seam 16 during the electronic heat sealingoperation. The uppermost edge of flange 22 is also serrated, as at 22a,to provide a plurality of teeth which form rectangular spotlike sealseach dimensioned one-sixteenth inch by three thirty-seconds inch. Theone-sixteenth inch dimension for each of the seal spots formed alongseam 16 is illustrated by the dimension Y in FIG. 4, and the threethirty-seconds inch dimension of each such seal spot extends transversethereto. Each tooth of the serrated flange 22 is spaced from theadjacent teeth by substantially one-sixteenth inch.

A die of the type shown in FIG. 3 is mounted in high frequency sealingand heating equipment, e.g., of the type marketed under the designationThermatron type Kl5lS by Willcox and Gibbs. This commercially availableequipment is, however, modified to add booster cylinders operative toincrease the force with which an opposing pair ofdies such as 20 pressinto the opposing plastic sheets 12 and 13 during fabrication of thelaminate. The serrated edges 21a and 22a along die rim 2! and die flange22 serve two functions, i.e., they tend to concentrate the appliedpressure to relatively small areas of the plastic material to be sealed,and, in addition, direct applied RF to the immediate area of suchpressure. The corrugations along'the edges of the dies thus press theupper and lower plastic layers 12 and 13 forcibly toward one anotherinto very close proximity, and simultaneously press the, fiber glassmaterial 14 to one side between the teeth of serrated portion 22a, andforcibly compress any remaining fiber glass material which may underlieany tooth in serrated section 220, so that essentially vinyl to vinylcontact is achieved along flange 22 to permit the upper and lowerplastic layers to seal to one another notwithstanding the fact thatfiber glass was interposed between the two layers in this region beforethe pressure was applied.

ln operation, hydraulic pressure is first applied to the dies for aninitial time period, e.g., three seconds, prior to application of RF.This assures that the die is very solidly bedded, to achieve fiber glasscompression and vinyl to vinyl contact before the die is actuallyenergized. If this solid bedding is not achieved prior to energizationof the die, arcing may occur with resultant melting or burning of theplastic layer underlying flange 22. After the initial three-second timelapse, the die is energized by application of RF thereto. Sealing isaccomplished, of course, as a function of both the power which isapplied and the time of its application. The shorter the time cycle, themore power required. Since relatively high power increases the incidenceof arcing, particularly if there is an inert material such as fiberglass between the plastic layers, power is applied for a relatively longperiod (e.g., a 5-second fusion cycle) and at a relatively low powerlevel.

By attention to all of the factors described, i.e., the serrated die,the increased pressure between the die and laminate, the initial timedelay to permit solid bedding, and the relatively long and low powerfusion cycle, it becomes possible for the first time to form a seam suchas 16 which extends directly through an intervening fiber glass layerwithout burning or melting the outer vinyl layers. It thus becomespossible to fabricate a sealed bag which has superior characteristics ofinsulation and waterproofness, and which exhibits these characteristicsover a longer period of time in usage; and, in addition, to fabricatesuch structures by a more rapid, labor saving, and less expensivetechnique than has been considered possible heretofore.

lclaim:

1. A carrier bag structure having a flexible insulating wall panelcomprising a unitary, generally flat surfaced mat of fiber glassmaterial, said panel including a cover of air and watertight flexiblethermoplastic sheet material completely surrounding and enclosing saidfiber glass mat, said cover including a pair of cover sections spacedfrom one another adjacent the opposing flat surfaces of said mat andhaving peripheral edges which overlie one another and are electronicallysealed to one another along peripheral seams spaced outwardly of andfree from the peripheral edges of said mat, each of said cover sectionsincluding regions which are depressed toward one another through saidfiber glass material to define supplemental seam regions extending alonglines positioned inward of the peripheral edges of both said coversections and of said mat, said supplemental seam regions beingelectronically sealed to one another through said fiber glass materialto trap a portion of said mat between said supplemental seam regions andthe electronically sealed peripheral seams of said cover sections,whereby said mat is sealed within said thermoplastic cover sections bymeans of said electronic peripheral seams and is prevented from shiftingin position or bunching up between said cover sections by means of saidelectronically sealed supplemental seam regions.

2. The structure of claim 1 wherein said supplemental seam regionscomprise a plurality of separate seal spots spaced from one anotheralong lines extending generally parallel to the peripheral edges of saidcover sections.

3. The structure of claim 1 wherein said mat and said cover sections areeach rectangularly shaped. said supplemental seam regions extending in arectangular configuration along lines parallel to all four edges of saidcover sheets and mat at positions relatively closely adjacent to theperipheral edges of said cover sections to trap in place a relativelynarrow peripheral band of said mat adjacent all four edges of said mat,the remaining main portion of said mat inward of said supple-

1. A carrier bag structure having a flexible insulating wall panelcomprising a unitary, generally flat surfaced mat of fiber glassmaterial, said panel including a cover of air and watertight flexiblethermoplastic sheet material completely surrounding and enclosing saidfiber glass mat, said cover including a pair of cover sections spacedfrom one another adjacent the opposing flat surfaces of said mat andhaving peripheral edges which overlie one another and are electronicallysealed to one another along peripheral seams spaced outwardly of andfree from the peripheral edges of said mat, each of said cover sectionsincluding regions which are depressed toward one another through saidfiber glass material to define supplemental seam regions extending alonglines positioned inward of the peripheral edges of both said coversections and of said mat, said supplemental seam regions beingelectronically sealed to one another through said fiber glass materialto trap a portion of said mat between said supplemental seam regions andthe electronically sealed peripheral seams of said cover sections,whereby said mat is sealed within said thermoplastic cover sections bymeans of said electronic peripheral seams and is prevented from shiftingin position or bunching up between said cover sections by means of saidelectronically sealed supplemental seam regions.
 2. The structure ofclaim 1 wherein said supplemental seam regions comprise a plurality ofseparate seal spots spaced from one another along lines extendinggenerally parallel to the peripheral edges of said cover sections. 3.The structure of claim 1 wherein said mat and said cover sections areeach rectangularly shaped, said supplemental seam regions extending in arectangular configuration along lines parallel to all four edges of saidcover sheets and mat at positions relatively closely adjacent to theperipheral edges of said cover sections to trap in place a relativelynarrow peripheral band of said mat adjacent all four edges of said mat,the remaining main portion of said mat inward of said supplemental seamregions being free of attachment from said cover sheets.
 4. Thestructure of claim 3 wherein said peripheral seams extend along all fouredges of said cover sections.
 5. The carrier bag structure of claim 1wherein a plurality of said insulating walls panels are interconnectedto one another by sewn seams, said sewn seams being confined topositions located between the peripheral seams and supplemental seamsregions of each such panel.
 6. The structure of claim 1 wherein saidthermoplastic sheet material is vinyl.